1. Field of the Invention
Example embodiments generally relate to an image forming apparatus and a damper, for example, for absorbing shock.
2. Description of the Related Art
A related-art image forming apparatus, such as a copier, a printer, a facsimile machine, or a multifunction printer having at least one of copying, printing, scanning, and facsimile functions, typically forms a toner image on a recording medium (e.g., a recording sheet) by electrophotography.
When a recording sheet is jammed in such image forming apparatus or when a toner cartridge needs to be replaced, for example, a user of the image forming apparatus may open an upper cover provided in an upper portion of the image forming apparatus to expose an interior of the image forming apparatus. However, a heavy scanner is often mounted on the upper cover, requiring the user to open the upper cover with a strong force. Moreover, when the user closes the upper cover, the upper cover may quickly rotate due to its weight and may damage the user or elements included in the image forming apparatus.
To address those problems, a damper for absorbing shock is generally provided on a rotary shaft of the upper cover. Thus, for example, one example of the image forming apparatus includes an upper cover and a body. The upper cover is rotatable about a rotary shaft and an arm. One end of the arm is attached to the upper cover in such a manner that the arm is rotatable about the rotary shaft of the upper cover. Another end of the arm is guided along a guide surface provided in the body. A torsion spring is provided on the rotary shaft of the upper cover and presses the other end of the arm toward the guide surface. Namely, the arm pressing the guide surface generates a force for rotating the upper cover in an open direction, in which the upper cover is opened with respect to the body. Thus, a user of the image forming apparatus may open the upper cover with a decreased force. When the user closes the upper cover, the force for rotating the upper cover in the open direction decreases a force for rotating the upper cover in a close direction caused by weight of the upper cover. Consequently, the upper cover does not close too quickly.
In some image forming apparatuses, a sheet stacker is provided between the upper cover and the scanner to save space. In this case, the scanner is slidable with respect to the upper cover, so that the user may easily identify and pick up a recording sheet on the sheet stacker.
However, when the scanner slides, a center of gravity of the scanner moves with respect to the upper cover. For example, when the scanner slides toward a rear side of the image forming apparatus in which the rotary shaft of the upper cover is provided, the center of gravity of the scanner also moves toward the rear side of the image forming apparatus. When the damper provides a damper performance optimized for opening the upper cover before the scanner starts sliding, the center of gravity of the scanner moved toward the rear side of the image forming apparatus amplifies a force for rotating the upper cover in the open direction applied by the damper. Consequently, the upper cover may quickly rotate toward the rear side of the image forming apparatus. Moreover, the center of gravity of the scanner moved toward the rear side of the image forming apparatus and the force applied by the damper to rotate the upper cover in the open direction may require the user to apply a strong force to close the upper cover.
Obviously, such unstable opening and closing of the upper cover are undesirable, and accordingly, there is a need for a technology to provide stable opening and closing of the upper cover even when the upper cover carries a heavy slidable device.